#include <my_header.h>

/* Usage: ./5_popen3 */
int main(void){   
    // 向5_sum的标准输入写数据
    FILE *pipe = popen("./5_sum", "w");
    ERROR_CHECK(pipe, NULL, "popen");
    // 3 4为3个大小的1字节数据 写道pipe
    fwrite("3 4", 1, 3, pipe);

    pclose(pipe);
    return 0;
}


